A hollow shaft (d0 = 2di where d0 and di are the outer and

A hollow shaft (d₀ = 2d_i where d₀ and d_i are the outer and inner diameters respectively) needs to transmit 20 kW power at 3000 RPM. If the maximum permissible shear stress is 30 MPa, d₀ is

P = Tω

20 × 10³ = T ×	2π × 3000
	60

∴ T = 63.662 N– m

Now	T	=	τ
	I_p		r

So,	63.662	=	30 × 10⁶	(r₀ = d),
	π/32(15d⁴₁)		d₁

∴ d₁ = 11.295 mm
∴ d₀ = 2d₁ = 22.59 mm